1981 xj650. Exhaust studs on one cylinder broke, both flush with head. Then extractor broke off in one. After drilling that out, there wasn't anything left to tap, so shop brazed in a threaded tube to replace bolt hole. Lasted a year, pulled out yesterday. Choice is try rebrazing or give up on the head. The head is due for a valve adjustment. So, I am thinking next project is swapping on a new head. If I can adjust the valves of new head on the bench, two birds with one stone. Can I? Can't see a reason clearances would change. I have a line on a complete head so would be measuring with camshafts bolted in on the bench. Only difference I can see is no timing chain, can't see that affecting clearance measurement. Thanks!